Heat treating furnace



Sept. 3, 1968 H. N. IPsEN HEAT TREATING FURNACE Filed April 2l, 1965 2 Sheets-Sheet l .E .Irbvswirow Sept. 3, 1968 H. N. IPsEN 3,399,875

HEAT TREATING FURNACE Filed April 21, 1966 2 Sheets-Sheet 2 lsz TTORBY/ Patented Sept. 3, 1968 HEAT TREATING FURNACE Harold N. Ipsen, deceased, late of Rockford, Ill., by the Illinois National Bank and Trust Co., executor, Rockford, Ill., assignor to Alco Standard Corporation, Philadelphia, Pa., a corporation of Pennsylvania Filed Apr. 21, 1966, Ser. No. 554,236 8 Claims. (Cl. 263-36) ABSTRACT OF THE DISCLOSURE A passage for admitting workpieces into a chamber of a vacuum heat treating furnace is closed by two doors, one a relatively light weight vacuum sealing door movable upwardly and downwardly to open and close the passage and also movable broadwise into tight engagement with the walls of the furnace around the passage in order to establish a gas-tight seal for the chamber. The other door is simply movable upwardly and downwardly across the passage between the vacuum door and the heating chamber and is made of relatively heavy heat insulating material to shield and insulate the vacuum door from the heat in the chamber.

This invention relates to heat treating apparatus or a furnace of the type in which workpieces are moved into a heat chamber and heated, usually in a vacuum or nonoXidizing atmosphere and more particularly, the invention relates to a door structure for such a heat treating apparatus.

The primary object of this invention is to provide a door which controls the entryway of the heating chamber, which is readily movable and which effectively seals the entryway against heat and gas passage therethrough.

Another object is to provide a door which is especially suited to meet the sealing requirements of vacuum heat treating and which is operated easily by simple, reciprocating actuators.

Other objects and advantages of the invention will become apparent from the following detailed description taken in connection with the accompanying drawings, in which:

FIGURE 1 is a cross-sectional view of a heat treating furnace embodying the invention.

FIG. 2 is a fragmentary perspective view of the entryway to the heat chamber of the furnace showing the doors in the closed position.

FIG. 3 is a fragmentary plan view of one edge of the door and entryway.

FIG. 4 is a side view of the vacuum door in the partially closed position.

In the apparatus shown in the drawings to illustrate the invention, the work to be treated is heated in a heat chamber 11 defined by an inner casing or internal baille 12 which is made of refractory material and which is disposed within a separate outer metal casing 14. The work is moved through an opening 15 in the baille and an alined opening 16 in the furnace housing 17, the two openings together constituting the entryway into the furnace chamber. Conventional heating elements 18 within the chamber 11 heat the work 10, usually carried in a tray, to the desired temperature while the tray is resting on a support 19.

The work is loaded into the heating chamber 11 through a cooling chamber 20 which is deiined by walls 21 having an opening 22 therethrough controlled by a door 24. This cooling chamber communicates with the entryway through the openings 15 and 16 whichA are alinedwith the opening 22. The work rests on rollers 25 journaled on a support 26 in the cooling chamber from which it can be moved easily into the heat chamber on additional rollers 27 rotatably mounted on the support 19.

The furnace chamber 14 is pressure sealed to allow heating of the workpieces in a substantial vacuum and, for this purpose, the chamber may be evacuated by a mechanical pump 29 connected in series with an oil diffusion pump 30. The pump 29 communicates with the furnace chamber through a port 31 and discharges through a conduit 32 connected to the diffusion pu-mp 30. The conduit 32 includes a illter 34 for removing any foreign matter that the air might carry from the furnace chamber. In order that the furnace may also be used to heat work in a controlled atmosphere as well as a vacuum, a fan 35 is disposed within the chamber 11 and is driven by a motor 36 mounted on the outside of the furnace to circulate the atmosphere within the heating chamber.

After the workpieces are heated suiliciently, they are transferred back into the cooling chamber 20 for quenching. The atmosphere in this chamber is circulated by va fan 41 driven by a motor 42 for cooling the workpieces. The workpieces then are removed from the cooling chamber through the opening 22 after opening the door 24 by energization of an actuator 44.

In accordance with the present invention, the entryway into the furnace is closed -by separate doors which control the openings 15 and 16 in the heat chamber baille 12 and the furnace wall 17, respectively, with the inner heat chamber door being adapted to limit the heat loss from the heat chamber and the outer door closing the opening in the furnace wall being a vacuum type for pressure sealing the furnace chamber. Accordingly, a heat insulating door 45 is provided for closing the opening 15 leading to the heat chamber and, a separate vacuum door 46 is supported for independent movement into engagement with the furnace wall 17 for sealing the opening 16 leading into the furnace chamber. The door 45 is comparatively heavy and operates with a simple vertical motion so that it acts principally as a heat shield. The door 46, on the other hand, is given a compound Imovement so that it not only moves vertically but also laterally to effect a good seal around the opening 16. Since the door 46 is shielded from the heat of the chamber 11 by the door 45, it may be quite light in weight and thus may be given this compound motion by a simple reciprocating actuator.

As shown in FIGS. 1 and 3, the heat insulating door 45 is made of a material capable of withstanding the temperatures to which the heat chamber is heated and is mounted for vertical movement within vertical channels 47. The latter are disposed on each side of the opening 15 and are formed by a flange 48 fixed to the baille 12 and extending around the opening and by a guide 49 fixed to the furnace housing 17. For moving the door, a suitable reciprocating actuator 50 mounted on a bracket 51 at the top of the furnace is connected to the door by a rod 52. Energizaton of this actuator effects vertical movement of the door between the raised or open position and the down or closed position. In the closed position, the insulating door is disposed in heat barrier relation with both the wall opening 16 and the chamber opening 15, the terms heat barrier relation as used herein and in the appended claims meaning that the insulating door moves across the openings and acts as a heat shield Without pressure sealing either of the openings with a gas-tight seal. The vacuum door 46 also is mounted for vertical movement relative to the opening 16 in the furnace housing 17 and, for this purpose, an actuator 54 mounted on a bracket 55 above the furnace is connected to the door by a rigid connecting rod 56 for moving the door into a closed position abutting the wall 17a and overlying the opening 16 therein. It is preferable that this actuator 54 be energized simultaneously with energization of the actuator 50 for the heat insulating door, for movement of the doors in unison. A gasket 57 carried by the vacuum door and encircling the opening 16 seals against the passage of gas around the door.

By positioning the vacuum door 46 outside of the heat insulating door 45, the gasket 57 and the vacuum door itself are protected from the intense heat generated within the heating chamber. To further protect the gasket, cooling' coils 58 preferably are fixed to the interior of the wall 17a of the furnace chamber and encircle the opening 16 to maintain the wall in the proximity of the gasket cool. In addition to the gasket being shielded against high temperatures, it also is protected against wear and being deformed as the door is moved to the closed position across the opening 16 and into contact with the furnace wall 17a.

Accordingly, the invention is further characterized by the manner in which the vacuum door 46 is supported and actuated across and toward the opening 16 between the open and closed positions. More particularly, the door first is moved away from the opening 16 and then up to uncover the opening. To close the latter, the door is .moved down in spaced relation to the wall 17a which defines the opening 16 and then is moved broadwise against this wall. All of these motions are effected by a conventional reciprocating actuator 54. Herein, the vacnum door is supported by a frame 59 to which a rod 56 leading from the actuator 54 is fixed. The frame moves vertically and carries the door down until it is alined with the opening 16, Continued downward movement of the frame shifts the door horizontally to seat the gasket 57 on the door against the wall 17a of the furnace. As shown in the drawings, the frame is guided for vertical movement by channels 60 fixed to the cooling chamber walls at each side of the opening 16. Riding in these channels are a pair of rollers 61 journaled on pins 62 fixed to the side of the frame.

To achieve the compound motion of the door 46 from the reciprocating motion of the frame 59, a parallelogram linkage 64 couples the frame to the door 4for moving the door horizontally las the frame is moved vertically to seat the gasket 57 properly. This parallelogram linkage comprises a pair of links 65 and 66 on each side of the door and each pivotally attached at opposite ends to the frame and door edges. The links are fixed at one end to the frame by being sandwiched between the rollers 61 and the frame edge on the pins 62 mounting the rollers. 'Ihe other ends of these links are pivotally attached by pins 67 to a door member 68 fixed to the outside of the vacuum door. A roller 69 is mounted on the lower pin 67 on each side of the door and contacts a flange 70 to the side of the door during the final downward movement of the frame.

Thus, to open the vacuum door, the actuator 54 is energized to move the rod 56 and connected frame 59 upward with the rollers riding alongside the channels 60. As the frame begins this upward movement, the weight of the vacuum door is supported by the rollers 69 resting on the flanges 70. With continued upward movement of the frame, the door weight is transferred to the links 65 and 66 and the links pivot counterclockwise about the pins 67 and pull the door away from the furnace wall 17a until the outer surface 68a of the door member 68 contacts the inner surface 59a of the frame. Thereafter the door and frame move upward together with the door being spaced from the furnace wall.

When the door and frame are lowered to close the door, the rollers 69 contact the flange 70 when the door is alined with the opening 16, and with further lowering of the frame, these rollers 69 roll inward toward the furnace wall 17a as the links 65 and 66 are pivoted clockwise about the pins 67. Continued movement of the frame ydownward after the gasket 57 contacts the furnace wall, effected by the actuator 54 acting through the rigid rod 56, causes the rollers 61 to be pressed tightly against the channels 60 to each side of the door thereby forcing the door toward the wall 17a to squeeze or load the gasket against the latter for pressure sealing the opening.

To adjust the loading force impressed on the gasket 57 when the vacuum door 46 is closed, screws 72 (FIG. l) holding the channels 60 first are loosened and, by turning the screws 74 seated in threaded holes in the brackets 75 fixed to the inner wall of the cooling chamber, the channels can be moved toward or away from the furnace wall 17a. Additionally, where the weight of the door causes it to swing about the links and be biased toward said frame in this embodiment, other yieldable means could be used to bias the door toward said frame if it was desirable not to move the frame to a position above the opening, but instead to move it to one side or below.

The entryway thus is effectively heat insulated and pressure sealed by the door structures described which are easily moved by energization of simple reciprocating actuators 50 and 54. It should be obvious that one actuator could be substituted for the two shown, if desired, with the only change in operation being that the heat insulating and vacuum doors would always be moved simultaneously while, with the use of two actuators, they can be moved individually if desired.

I claim as my invention:

1. A heat treating furnace, having in combination, a gas-tight walled structure enclosing a heating chamber, said structure including a wall with an opening through which workpieces can be moved into said chamber, heating means for raising the temperature of said workpieces within said chamber, and means for closing said opening comprising a heat insulating door and a vacuum door disposed on opposite sides of the opening and the wall with the heat insulating door being located alongside the chamber side of said wall and with the vacuum door being located alongside the opposite side of the wall, means for mounting said vacuum door for movement to a position extending across the opening and into engagement with said wall for sealing against gas flow through the opening, and means for mounting said heat insulating door for movement into heat barrier relation with both said opening and said heating chamber and into a position across said opening between the heating chamber and the vacuum door thereby to shield the latter from the heat of the chamber.

2. The combination as defined in claim 1 wherein the heating chamber is defined by a separate casing disposed within said structure and having an opening therein alined with said opening in said wall and wherein the heat insulating door is moved into heat barrier relation across said casing opening.

3. The combination as defined in claim 1 including sealing means between said vacuum door and said wall and encircling said wall opening.

4. The combination as defined in claim 1 wherein said means Ifor mounting said vacuum door includes mechanism for moving the door across and in alinement with said opening and then toward said opening into engagement with said wall to close said opening.

5. In a heat treating furnace, the combination of, a gas-tight walled structure enclosing a heating chamber, said structure including a wall with an opening through which workpieces can be moved into said chamber, said heating chamber being defined by a separate casing disposed within and surrounded by said structure and having an opening therein alined with the opening in said wall, heating means for raising the temperature of said workpieces within said chamber, means for closing said openings comprising a heat insulating door and a vacuum door disposed on opposite sides of said wall with the heat insulating door being located within said gas-tight structure alongside the chamber side of said wall and with the vacuum door being located alongside the opposite side of said wall, means for mounting said vacuum door for movement rst to a position extending across said wall opening and then toward said wall into gas-tight sealing engagement with the Wall for sealing against gas flow through the wall opening, and means for mounting said heat insulating door for movement into heat barrier relation across each of said openings and into a position between said heating chamber and said vacuum door thereby to shield the latter from the heat of the chamber.

6. The combination as defined in claim 5 wherein said means for mounting said vacuum door includes a frame mounted for movement across said wall opening, a parallelogram linkage connecting said door and frame for movement of said door bodily with said frame and also toward and away from said frame while being held parallel thereto, and an abutment stopping movement of said door across said wall opening when it alines with the Alatter on being moved to the closed position whereby upon further movement of said frame said door is moved toward said wall by said parallelogram mechanism.

7. For use with a wall structure defining an opening therethrough, the combination of, a door, a frame, a plurality of parallel extending links pivotally attached at one end to said frame and at the other end to said -door for supporting the door for movement toward and away from said frame and in parallel relationship thereto, guide means supporting said frame for movement along said wall structure to move said door from a first position to one side of said opening to a second position alined with said opening, means biasing said door toward said frame, and an abutment contacting said door and stopping movement thereof across said opening when the door alines with the opening whereby said door will be shifted toward and into engagement with said wall structure on further movement of said frame toward said second position.

8. The combination as ldefined in claim 7 wherein said frame is supported in said guide means for movement above said opening and said door isbiased toward said frame by its own weight causing the links to pivot about theframe.

References Cited UNITED STATES PATENTS 871,421 11/ 1907 Koppers.

890,175 6/1908 Ries T- 110-173 1,455,290 5/ 1923 Hieb. 1,795,324 3/1931 Wilhelm 110-173 2,373,891 4/ 1945 Heineman 34-92 2,398,874 4/ 1946 Weyhing. 2,804,855 9/1957 Bergman 110-173 XR 3,234,661 2/ 1966 Nerge 34-92 XR 3,301,541 l/1967 Ipsen 13-31 XR FREDERICK L. MATTESON, JR., Primary Examiner.

A. D. HERRMANN, Assistant Examiner. 

